This invention relates to a process for cleaning radiopharmaceutical reusable shipping containers which are generally referred to as pigs; and more particularly for cleaning pigs utilized for shipping radioactive drugs having relative short half lives, typically on the order of no more than a few days.
Radioactive drugs are typically shipped by pharmacies to hospitals, clinics and medical offices, frequently for diagnostic purposes. The drugs are shipped in pigs, each of which has a lead surround for radiation shielding and contains an inner chamber that may contain a syringe or vial which is suitable for dispensing an individual dose of a radioactive labeled drug.
The radiopharmaceutical pig typically is a two-part assembly, with an upper portion removably attached to the lower portion. The assembled pig includes a sealed internal chamber comprising a syringe containment enclosure suitable for carrying a syringe, and a lead radiation shield surrounding the chamber. The shield may be surrounded by an exterior plastic protective shell.
When a prescription is to be filled, a syringe or vial is placed in the lower portion of the syringe containment enclosure of the pig and the pig is assembled by threading the upper portion to the lower portion.
At the hospital or other medical facility, the pig is disassembled and the syringe is removed. After the dose is injected into the patient, the syringe usually contains a small amount of residual radioactive drug and is biologically contaminated, usually with blood, from coming into contact with the patient. It is put back in the bottom portion of the pig, and the spent pig is assembled and sent back to the pharmacy.
The spent pig is not suitable for reuse until any blood, microorganisms and residual radiation, and any other contaminants have been removed. The combination of radioactive material with other contaminants makes the cleaning of the returned pigs very difficult.
A prior art method for cleaning the spent pigs consists of the following steps:                The pigs are returned to the pharmacy in transport boxes.        The boxes and their internal contents are surveyed for radioactivity using a Geiger-Muller survey meter.        Radioactivity contaminated boxes and pigs are removed and stored until the radioactivity has decayed to background level.        The residual contents of the pigs are dumped into a lead or other radiation attenuating barrel.        The pigs are checked with a Geiger-Muller survey meter for radioactivity contamination and visually inspected for the presence of blood.        Pigs contaminated with blood are treated in a 10% solution of bleach in water.        The pig is then reused by placing a new syringe or vial containing a radioactive drug ordered by a customer within each pig which has not been found to be contaminated, and the pig is sent to the customer.        
Unfortunately pigs which have been cleaned by this process have a relatively high incidence of contamination, indicating that the prior art cleaning process needs improvement.
Another prior art solution to the pig cleaning problem has been to utilize a disposable insert that fits into the cavity of the pig, with the syringe being disposed within the insert. Such an arrangement is shown in U.S. Pat. No. 7,268,359 to Fu et al., FIGS. 1 and 2 of which appear as FIGS. 2 and 3 of the present application respectively—so that the numbered elements of these figures are as described in the Fu et al. patent. The disclosure of U.S. Pat. No. 7,268,359 is hereby incorporated into the present application.
As seen in FIGS. 2 and 3, the disposable insert of Fu et al. comprises an upper lining 12 and a lower lining 14 which nest together to form a chamber for a syringe which is placed in the lower lining 14; the insert being placed in the chamber formed by the upper radiation shield portion 16 and the lower radiation shield portion 18.
However, the insert system of Fu et al. does not provide a perfect seal and does not completely remove contaminants. In a study by Pickett et al. entitled The Incidence of Blood Contamination of Lead Unit Dose Containers With and Without Single-Use Protective Inserts Used with Commercially Prepared Radiopharmaceutical Unit Doses, Journal of Nuclear Medicine Technology, Volume 26, No. 3, Sept. 1998, 1% of the pigs utilizing inserts arrived at the nuclear medicine department with detectable blood contamination. A substantially lower contamination level is desirable. Moreover, the insert system does not address bacterial, viral, blood, radioactive and other contaminants that exist on the outside of the pigs. Consequently, subsequent doses of radiopharmaceuticals may be distributed in pigs that are contaminated with biological and/or radioactive contaminants.
Accordingly, an object of the present invention is to provide a process for cleaning radiopharmaceutical pigs that may or may not have disposable inserts.